1. Field of the Invention
This invention relates to a surface examining apparatus capable of examining a surface including depth information, for example, a surface examining apparatus which can be used for ophthalmic examination such as the examination of glaucoma.
2. Related Background Art
In the heretofore known ophthalmic examining apparatus, an eye fundus camera has been widely used as the means for recording information of an eye to be examined, for example, the information of the eye fundus. To gather the uneven state of the eye fundus, there have been practiced a method simply stereo-photographing the eye fundus and gathering the uneven state of the eye fundus from the image of the eye fundus and a method of projecting a striped pattern onto the eye fundus and gathering the uneven state of the eye fundus from the shape ofthe image of the striped pattern. However, in the former method, it is difficult to transform the depth of the unevenness into the form of a numerical value. In the latter method, it is necessary to accurately superpose and project a striped pattern. In a case where, for example, the state of the depth profile of an optic disc, which is information for judgment of glaucoma is to be examined, the depth profile is wiped out by an illuminating light for the observation of the eye fundus image. This leads to the disadvantage that measurement becomes impossible or discontinuity occurs due to the measurement conforming to the interval between the stripes.
In the field of eye fundus cameras U.S. Pat. No. 4,213,678 discloses a known technique of scanning and illuminating the eye fundus by a light, but this patent only discloses the detection of the eye fundus image and does not disclose the detection of the depth distribution information of the eye fundus.
Also, in Japanese Laid-Open Patent Application No. 16103/1981, there is disclosed as an eye refractometer, the technique of projecting a predetermined index mark onto a predetermined portion of the eye fundus, providing light beam separating means in the optical path for receiving the reflected light from the eye funduds, and finding the refractive power of the eye from the position of the image of the index mark onlight position detecting means. However, this publication of course does not disclose the technical idea of detecting the depth distribution informaiton of the eye fundus. Further, an eye refractometer and an eye fundus camera differ fundamentally from each other, and this disclosure simply cannot be combined with U.S. Pat. No. 4,213,678.